Oh yeah theres actually quite a few hidden quests you can stumble across if you know where to look! The coolest one i found was this prison area in niflheim, which opens up after the main story and has some pretty wild revelations about one of the characters. If youre exploring svartalfheim, theres this really touching quest about giving someone a proper sendoff, which actually leads to a special ending scene if you complete it.

Something i thought was neat is this whole thing with the realm seeds, where you gotta track down these gateway pieces scattered around the worlds. Makes getting around so much easier once you figure it out. And if you're into combat challenges, there are these leftover asgardian forces you can hunt down across different realms, which is pretty satisfying to clear out.

One of my favorites has to be this mysterious orb puzzle in vanaheim, the reward is totally worth the effort by the way. Just remember that a lot of these quests wont show up right away, you'll need to poke around in places like those weird sandstorms in alfheim or backtrack to some spots after you've gotten stronger abilities. Trust me though, the exploration really pays off!